Crystal structure of bis(4-benzoylpyridine-κN)bis(methanol-κO)bis(thiocyanato-κN)cobalt(II)

The crystal structure of the title compound consists of discrete octahedral complexes that are linked by intermolecular O—H⋯O hydrogen bonding into layers.

The crystal structure of the title compound, [Co(NCS) 2 (C 12 H 9 NO) 2 (CH 3 OH) 2 ], consists of cobalt(II) cations that are octahedrally coordinated by two N-terminal bonding thiocyanato anions, two methanol molecules and two 4-benzoylpyridine ligands into discrete complexes that are located on centres of inversion. These complexes are further linked by O-HÁ Á ÁO hydrogen bonding between the hydroxy H atom of the methanol ligand and the carbonyl O atom of the 4-benzoylpyridine ligand of a neighboring complex into layers parallel to (101). No pronounced intermolecular interactions are observed between these layers.

Chemical context
The synthesis of magnetic coordination compounds is still a major topic in coordination chemistry. For example, compounds in which the metal cations are linked by smallsized anionic ligands are of special interest because cooperative magnetic properties can be expected (Palion-Gazda et al., 2015;Massoud et al., 2013). In this context, we and others have reported on a number of one-or two-dimensional thiocyanate coordination compounds that, dependent on the nature of the metal cation and the neutral co-ligand, show different magnetic properties (Palion-Gazda et al., 2015;Massoud et al., 2013;Suckert et al., 2016;Werner et al., 2015a,b,c,d). In the majority of compounds having a chain structure, the metal cations are linked by pairs of anionic ligands, whereby the coligands as well as the N and the S atoms of the thiocyanate anions are always trans-coordinating. Surprisingly, with 4-benzoylpyridine and cobalt thiocyanate we obtained a compound in which the N-donor co-ligands are still trans to each other, whereas the N and the S atoms of the anionic ligands show a cis-arrangement (Rams et al., 2017). Like many other Co chain polymers, this compound represent an antiferromagnetic phase of single chain magnets with magnetic properties similar to that of related cobalt compounds with an all trans-coordination. Later on, we accidentally obtained a further crystalline phase with 4-benzoylpyridine as a co-ligand by reaction in methanol. Here we report on these results.

Structural commentary
The asymmetric unit of the title compound, [Co(NCS) 2 (C 12 H 9 NO) 2 (CH 3 OH) 2 ], consists of one cobalt(II) cation that is located on a center of inversion as well as of one thiocyanate anion, one methanol molecule and one neutral 4-benzoylpyridine ligand in general positions. The Co II cation ISSN 2056-9890 is octahedrally coordinated by two terminal N-bonded anionic ligands, the O atoms of two methanol molecules and the N atoms of two 4-benzoylpyridine ligands (Fig. 1). The Co-N bond lengths to the thiocyanate anions are significantly shorter [2.062 (2) Å ] than those to the pyridine N atom of the neutral 4-benzoylpyridine ligand [2.1875 (18) Å ]. This is expected and in agreement with bond lengths reported in the closely related structure of [Co(NCS) 2 (C 12 H 9 NO) 2 (CH 3 CN) 2 ]  where methanol is replaced by acetonitrile, and also for related compounds reported in the literature (Soliman et al., 2014). The 4-benzoylpyridine ligand is not planar, with the phenyl rings inclined by 61.34 (9) . This value is in agreement with those retrieved from literature which vary between 40.4 and 74.8 (Escuer et al., 2004).

Supramolecular features
In the crystal structure of the title compound, the discrete complexes are linked by intermolecular O-HÁ Á ÁO hydrogen bonds between the hydroxyl H atom of the methanol molecule and the carbonyl oxygen atom of a 4-benzoylpyridine ligand of a neighboring complex. Each of the complexes is linked to four symmetry-related complexes into layers parallel to (101) ( Fig. 2 and Table 1). Between these layers no pronounced intermolecular interactions are observed (Fig. 3). View of one discrete complex with labelling and displacement ellipsoids drawn at the 50% probability level. [Symmetry code: (i) Àx + 1, Ày, Àz + 1.] Table 1 Hydrogen-bond geometry (Å , ).

D-HÁ
coordinated by the N atoms of four 4-benzoylpyridine ligands and the N atoms of two thiocyanate anions (Drew et al., 1985;Soliman et al., 2014). In the third compound, Cu(II) cations have a square-planar coordination sphere defined by two 4-benzoylpyridine ligands and two thiocyanate anions (Bai et al., 2011). Finally, we have reported on a compound with a one-dimensional structure, in which the Co(II) cations are linked by -1,3-bridging thiocyanate anions (Rams et al., 2017), as well as a compound very similar to the title structure in which Co II cations are coordinated into discrete complexes by two thiocyanate anions, two 4-benzoylpyridine ligands and two acetonitrile molecules .

Synthesis and crystallization
Co(NCS) 2 and 4-benzoylpyridine were purchased from Alfa Aesar. Crystals of the title compound suitable for single crystal X-ray diffraction were obtained by reaction of 26.3 mg Co(NCS) 2 (0.15 mmol) with 27.5 mg 4-benzoylpyridine (0.15 mmol) in methanol (1.5 ml) after a few days.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. The C-bound hydrogen atoms were positioned with idealized geometry and were refined with fixed isotropic displacement parameters U iso (H) = 1.2 U eq (C) for aromatic and U iso (H) = 1.5 U eq (C) for methyl H atoms using a riding model. The methyl hydrogen atoms were allowed to rotate but not to tip. The O-H hydrogen atom was located in a difference map. Its bond length was set to the ideal value of 0.84 Å and finally, it was refined with U iso (H) = 1.5 U eq (O) using a riding model.

Bis(4-benzoylpyridine-κN)bis(methanol-κO)bis(thiocyanato-κN)cobalt(II)
Crystal data Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )